Halo, nitro, and halonitro S-alkyl thiocarbonates

ABSTRACT

Unsymmetrical carbonates of the formula ##STR1## are prepared by the following reaction sequence ##STR2## where R and R&#39; can each be --CH 2  C(NO 2 ) 3 , CH 2   CF(NO..2) 2 , --CH 2  CF 2  (NO 2 ), --CH 2  CCl(NO 2 ) 2 , --CH 2  CF 3 , --CH 2  CCl 3 , --CH 2  C(NO 2 ) 2  CH 3 , or --CH 2  CF 2  CF 2  H, provided that R≠R&#39; and wherein R&#34; is a lower alkyl group of from 1 to 6 carbon atoms. 
     Also included are symmetrical 1,3-bis(halo- and nitroalkyl carbonyldioxy)-2,2-dinitropropanes of the formula ##STR3## which are synthesis by the following reaction sequence ##STR4## wherein R and R&#34; are as defined above. The carbonates of this invention are useful as energetic additives to propellants and explosive.

This is a division of application Ser. No. 224,776, filed Jan. 13, 1981,now U.S. Pat. No. 4,332,744.

BACKGROUND OF THE INVENTION

This invention relates to organic carbonates and more particularly tonitro substituted organic carbonates.

In order to prepare unsymmetrical carbonates, it is necessary to react achloroformate of an alcohol with a second alcohol. The general methodfor preparing chloroformates is to react an alcohol with an excess ofphosgene (poisonous gas) in the presence of a base as an acid acceptor.Inevitably a greater or lesser amount of the carbonate is formed, as aby-product, which lowers the yield and requires separation of theproduct. In addition, nitroalcohols in the presence of base, have atendency to deformylate, which also lowers the yield of chloroformate. Athird factor is that nitro substituted diols such as2,2-dinitropropan-1,3-diol form as major products linear carbonates andcyclic carbonates.

SUMMARY OF THE INVENTION

An object of this invention is to provide new organic compounds.

Another object of this invention is to provide new explosive materials.

A further object of this invention is to provide unsymmetricalpolynitrocarbonates.

Still another object is to provide a method of synthesizingunsymmetrical polynitrocarbonates.

Yet a further object of this invention is to provide novel symmetrical,1,3-bis(halo- and nitroalkyl carbonyldioxy)-2,2-dinitropropanes.

Still a further object of this invention is to provide a method ofsynthesizing novel symmetrical 1,3-bis(halo- and nitroalkylcarbonyldioxy)-2,2-dinitropropanes.

These and other objects of this invention are achieved by providing (1)novel unsymmetrical polynitrocarbonates of the formula ##STR5## by thefollowing reaction sequence ##STR6## wherein R≠R' and wherein R and R'are each selected from the group consisting of --CH₂ C(NO₂)₃, CH₂CF(NO₂)₂, --CH₂ CF₂ (NO₂), --CH₂ CCl(NO₂)₂, --CH₂ CF₃, --CH₂ CCl₃, --CH₂C(NO₂)₂ CH₃, and --CH₂ CF₂ CF₂ H, and wherein R" is a lower alkyl offrom 1 to 6 carbon atoms; and (2) symmetrical 1,3-bis(halo- andnitroalkyl carbonyldioxy)-2,2-dinitropropanes of the formula ##STR7##which are synthesized by the following reaction sequence ##STR8##wherein R and R" are as defined above.

The carbonates of this invention are useful as energetic additives topropellants and explosives.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The reaction sequences of this invention summarized as follows:

    ______________________________________                                        STEP   UNSYMMETRICAL   SYMMETRICAL                                            ______________________________________                                                ##STR9##                                                                                      ##STR10##                                              (1)                                                                                  ##STR11##                                                                                     ##STR12##                                              (2)                                                                                  ##STR13##                                                                                     ##STR14##                                              (3)                                                                                  ##STR15##                                                                                     ##STR16##                                             wherein R≠R' and R and R' can be --CH.sub.2 C(NO.sub.2).sub.3,     --CH.sub.2 CF(NO.sub.2).sub.2, --CH.sub.2 CF.sub.2 (NO.sub.2), --CH.sub.2     CCl(NO.sub.2).sub.2, --CH.sub.2 CF.sub.3, --CH.sub.2 CCl.sub.3, --CH.sub.2     C(NO.sub.2).sub.2 CH.sub.3, and --CH.sub.2 CF.sub.2 CF.sub.2 H, and     wherein R" is a lower alkyl group of from 1 to 6 carbon atoms, but     preferably a lower alkyl of from 1 to 3 carbon atoms.

The alcohols ROH and R'OH, which may be used in the synthesis are

2,2,2-trinitroethanol,

2-fluoro-2,2-dinitroethanol,

2,2-difluoro-2-nitroethanol,

2-chloro-2,2-dinitroethanol,

2,2,2-trifluoroethanol,

2,2,2-trichloroethanol,

2,2-dinitropropanol, and

2,2,3,3-tetrafluoropropanol.

Obviously, for unsymmetrical carbonates ROH must not be the same asR'OH. Note that the alcohol used in step (1) for the production ofsymmetrical 1,3-bis(halo and nitroalkylcarbonyldioxy)-2,2-dinitropropanes is 2,2-dinitropropan-1,3-diol.

The syntheses of the unsymmetrical and the symmetrical carbonates differin the combination of alcohols used, but the same reaction conditionsare used.

The solvents used in all reaction steps must be inert. Examples ofsuitable solvents are methylene chloride, chloroform,1,2-dichloroethane, and benzene.

In step (1) a Friedl-Crafts catalyst was used in a non-basis solution.Examples of suitable catalysts are ferric chloride, stannic chloride,titanium tetrachloride, and zinc chloride. Anhydrous ferric chloride wasused in the examples 1-9.

Examples 1, 2, and 3 illustrate that the reaction between the alcoholand the alkyl chlorothiolformate is vigorous at ambient temperature inthe presence of the catalyst (anhydrous FeCl₃). The reaction mixtureswere stirred at ambient temperature for 30 to 60 minutes and yields of90 percent or more were obtained.

The general formulas of the products of step (1) are ##STR17## for theunsymmetrical synthesis and ##STR18## for the symmetrical synthesis.Because of the commercial availability of S-ethyl chlorothiolformate,the following products should be easiest to produce

S-ethyl 2,2,2-trinitroethyl thiolcarbonate,

S-ethyl 2-fluoro-2,2-dinitroethyl thiolcarbonate

S-ethyl 2,2-fluoro-2-nitroethyl thiolcarbonate,

S-ethyl 2-chloro-2,2-dinitroethyl thiolcarbonate,

S-ethyl 2,2,2-trifluoroethyl thiolcarbonate,

S-ethyl 2,2,2-trichloroethyl thiolcarbonate,

S-ethyl 2,2-dinitropropyl thiolcarbonate,

S-ethyl 2,2,3,3-tetrafluoropropyl thiolcarbonate, and finally the

Bis(S-ethyl thiolcarbonate) of 2,2-dinitropropan-1,3-diol, ##STR19##

In step (2) the alkyl thiolcarbonate is refluxed with an excess ofsulfuryl chloride (SO₂ Cl₂) in an inert solvent until the alkylthiolcarbonate is converted to the corresponding chloroformate. InExamples 4, 5, and 6, six hours of refluxing produced the products ingood yield.

For reaction step (2) the general formula for the product of theunsymmetrical process is ##STR20## wherein R is as defined above. Morespecifically the compounds are 2,2,2-trinitroethyl chloroformate,

2-fluoro-2,2-dinitroethyl chloroformate,

2,2-difluoro-2-nitroethyl chloroformate,

2-chloro-2,2-dinitroethyl chloroformate,

2,2,2-trifluoroethyl chloroformate,

2,2,2-trichloroethyl chloroformate,

2,2-dinitropropyl chloroformate, and

2,2,3,3-tetrafluoropropyl chloroformate.

The product of the symmetrical process is ##STR21##

In step (3) the chloroformate is reached with an alcohol to produce theproduct carbonate. As illustrated by examples 7, 8, and 9, the reactionmixture should be cooled and the addition rate of the alcohol to thechloroformate should be adjusted so that the reaction mixture does notoverheat. A base, such as pyridine, is added to the mixture to act as anacid acceptor for the HCl generated by the reaction.

In the case of the unsymmetrical synthesis the general reaction of step(3) is ##STR22## wherein R and R' are as defined above and R≠R'.

Preferred carbonates include

2-fluoro-2,2-dinitroethyl-3,3,3-trinitroethylcarbonate

2,2-difluoro-2-nitroethyl-3,3,3-trinitroethylcarbonate,

2-chloro-2,2-dinitroethyl-3,3,3-trinitroethylcarbonate,

2,2-dinitropropyl-3,3,3-trinitroethylcarbonate,

2,2-difluoro-2-nitroethyl-3-fluoro-3,3-dinitroethylcarbonate,

2-chloro-2,2-dinitroethyl-3-fluoro-3,3-dinitroethylcarbonate,

2,2-dinitropropyl-3-fluoro-3,3-dinitroethylcarbonate,

2-chloro-2,2-dinitroethyl-3,3-difluoro-3-nitroethylcarbonate,

2,2-dinitropropyl-3,3-difluoro-3-nitroethylcarbonate, and

2,2-dinitropropyl-3-chloro-3,3-dinitroethylcarbonate.

The general reaction of step (3) for the symmetrical 1,3-bis(halo- andnitroalkyl carbonyldioxy)-2,2-dinitropropanes synthesis is ##STR23##where R is as defined above. Specifically the symmetrical 1,3-bis(halo-and nitroalkyl carbonyldioxy)-2,2-dinitropropanes are

1,3-bis(3,3-trinitroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3-fluoro-3,3-dinitroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3,3-difluoro-3-nitroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3-chloro-3,3-dinitroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3,3,3-trifluoroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3,3,3-trichloroethyl carbonyldioxy)-2,2-dinitropropane,

1,3-bis(3,3-dinitropropyl carbonyldioxy)-2,2-dinitropropane, and

1,3-bis(3,3,4,4-tetrafluoropropyl carbonyldioxy)-2,2-dinitropropane.

The three step process used to synthesis the unsymmetrical carbonates ofthis invention, may be used to synthesis a wide variety of unsymmetricalcarbonates. However, the alcohol used in step (1) to prepare the S-alkylthioformate should have at least one electronegative substituent, suchas NO₂, F, etc. The presence of the substituent inhibits chlorination ofthe functional group, which otherwise would give rise to side-products.

The general nature of the invention having been set forth, the followingexamples are presented as specific illustrations thereof. It will beunderstood that the invention is not limited to these examples but issusceptible to various modifications that will be recognized by one ofordinary skill in the art.

EXAMPLE 1 S-ethyl 2,2,2-trinitroethyl thiolcarbonate ##STR24##

To a stirred solution of 9.2 g of 2,2,2-trinitroethanol in 10 ml of1,2-dichloroethane was added 6.5 ml of ethyl chlorothiolformate and oneml of a 50% anhydrous ferric chloride solution in nitromethane. Avigorous reaction immediately ensued. The solution was stirred for onehour and then taken up in methylene chloride and washed consecutivelywith dilute hydrochloric acid and five 60 ml portions of water. Afterdrying with anhydrous magnesium sulfate, the organic solution wasfiltered and the solvents removed in vacuo. The residue was crystallizedfrom chloroform/hexane solution to give 12.52 g (90%) of the titlecompound: m.p. 36°. H-NMR (acetone d₆): δ=5.96 (S, 2H--CH₂ C(NO₂)₃),2.93 (q, 2H, --SCH₂ --), 1.28 (t, 3H, --CH₃).

Calc for C₅ H₇ N₃ O₈ S: C, 22.31, H, 2.62; N, 15.61; S, 11.91. Found: C,22.19; H, 2.57; N, 15.30; S, 11.65.

EXAMPLE 2 S-ethyl 2-fluoro-2,2-dinitroethyl thiolcarbonate ##STR25##

To a stirred solution of 7.7 g (0.05 mol) fluorodinitroethanol in 10 mlof methylene chloride was added 6.5 ml of ethyl chlorothiolformate andone ml of a 50% ferric chloride solution in nitromethane. A vigorousreaction immediately ensued that was essentially over in a few minutes.To insure complete reaction, stirring was continued for 30 minutes. Thereaction mixture was taken up in methylene chloride and washedconsecutively with 100 ml of dilute hydrochloric acid and five 100 mlportions of water. After drying with anhydrous magnesium sulfate andfiltering, the organic solvents were removed in vacuo. The residueweighing 12.07 g (99.7%) was of >98% purity by GLC analysis.

H-NMR (CDCl₃): δ=5.24 (d, 2H, --CH₂ --CF), 2.89 (q, 2H, --S--CH₂ --),1.30 (t, 3H, --CH₃).

Calcd for C₅ H₇ FN₂ O₆ S: C, 24.79; H, 2.91; F, 7.85; N, 11.57; S,13.24. Found: C, 24.83; H, 2.96; F, 7.69; N, 11.68; S, 13.40.

EXAMPLE 3 bis(S-ethyl thiolcarbonate) of 2,2-dinitro-1,3-propandiol##STR26##

To a stirred solution of 4.0 g (0.024 mol) of 2,2-dinitropropan-1,3-diolin 25 ml of methylene chloride/nitromethane 4/1 was added 5.8 ml ethylchlorothiolformate and one ml of a solution of 50% ferric chloride innitromethane. After an initial vigorous reaction, the solution wasstirred for an additional 30 minutes at ambient temperature. Thesolution was taken up in methylene chloride and washed with a 100 mlportion of dilute hydrochloric acid and five 100 ml portions of water.After drying and filtering, the solvent was removed in vacuo at 0.05torr. The residue weighed 8.3 g (100%). The purity of the residuewas >98% by GLC analysis.

H-NMR (CDCl₃): δ=5.08 (S, 4H, --O--CH₂ --C(NO₂)₂ CH₂ O--), 2.87 (d, 4H,--S--CH₂ --), 1.29 (t, CH, --CH₃).

(Calc. for C₉ H₁₄ N₂ O₈ S₂ : C, 31.57; H, 4.12; N, 8.19; S, 18.73.Found: C, 31.76; H, 4.30; N, 8.06; S, 18.77.

EXAMPLE 4 2-fluoro-2,2-dinitroethyl chloroformate ##STR27##

A solution of 13.82 g (0.057 mol) S-ethylfluorodinitroethyl-thiolcarbonate in 50 ml of 1,2-dichloroethane and 20ml of sulfuryl chloride was refluxed for 6 hours. After cooling, excesssulfuryl chloride and solvent was removed on a rotavac. The residue wasdistilled through a short column, 58° at 2 torr. To the yellowishdistillate was added 2 ml cyclohexane and this was redistilled to give11.59 g (94%) of product. GLC analysis indicated a purity of 99%.

I.R. (film): ν_(max) =1780, 1605, 1310 cm⁻¹.

H-NMR (CDCl₃): δ=5.36 (d, FC--CH₂ --).

EXAMPLE 5 2,2,2-trinitroethyl chloroformate ##STR28##

To a solution of S-ethyl trinitorethylthiolcarbonate (27.85 g, 0.098mol) in 50 ml of 1,2-dichloroethane was added 30 ml of sulfurylchloride. The reaction solution was refluxed for six hours, cooled, andvolatiles removed in vacuo. The residue was distilled through a shortpath column, 78° at 0.8 torr, to give 24.23 g of product. GLC analysisindicated a purity of 96.5%; corr. yield was 97.4%.

I.R. (film): ν_(max) =1783, 1608, 1300 cm⁻¹.

H-NMR (CDCl₃): δ=5.73 (S, --CH₂ --).

EXAMPLE 6 2,2-dinitropropyl chloroformate ##STR29##

A solution of S-ethyl 2,2-dinitropropylthiolcarbonate in 50 ml of1,2-dichloroethane and 20 ml of sulfuryl chloride was refluxed for 6hours. After cooling and removal of volatiles in vacuo the residue wasdistilled through a short path column to give 10.65 g (90%) of product;bp 82° at 0.2 torr.

I.R. (film): ν_(max) =1779, 1570, 1323 cm⁻¹

H-NMR (CDCl₃) δ=5.08 (S, 2H, --CH₂ --), 2.25 (S, 3H, --CH₃).

EXAMPLE 7 1,3-bis(3,3,3-trinitroethyl carbonyldioxy)-2,2-dinitropropane##STR30##

Pyridine (2.1 ml) was added to a slurry of 2,2-dinitropropan-1,3-diol in50 ml of CH₂ Cl₂ at 10° C. After the diol had dissolved, a solution oftrinitroethyl chloroformate (6.46 g, 26.6 mmol) in 7 ml of methylenechloride was added dropwise with stirring. The temperature was heldbelow 15° during the addition. The solution was then stirred for 3.5hours. Volatiles were then removed and the residue was washed withdilute hydrochloric acid and water and then air dried. The solid wasrecrystallized from methylene chloride to give 5.1 g of product (83%),m.p. 154°-5°.

H-NMR (acetone-d₆): δ=5.97 (S, 4H, CH₂ C(NO₂)₃), 5.40 (S, 4H, CH₂)

I.R. (fluorolube): ν_(max) =1780 cm⁻¹.

EXAMPLE 8 2,2-dinitropropyl-3,3,3-trinitroethylcarbonate ##STR31##

To a solution of trinitroethyl chloroformate (6.46 g, 26.5 mmol) and2,2-dinitropropanol (4.5 g, 30 mmol) in 25 ml of methylene chloride wasadded dropwise a solution of pyridine (2.24 ml) in methylene chloride (7ml) at or below 5°. Then the solution was stirred for 3 hr at ice bathtemperature and at ambient temperature for an additional hour. Thesolution was taken up in methylene chloride and washed consecutivelywith 100 ml of dilute hydrochloric acid and five 100 ml portions ofwater. The organic layer was dried (magnesium sulfate), filtered, andthe volatiles removed in vacuo. The solid residue was recrystalized fromchloroform to give 5.68 g (60%) of product, m.p. 107°.

Calc. for C₆ H₇ N₅ O₁₃ : C, 20.18; H, 1.98; N, 19.61. Found: C, 19.87;H, 1.82; N, 19.85.

H-NMR (CDCl₃): δ=5.47 (S, 2H, CH₂ C(NO₂)₃), 5.04 (S, 2H, O--CH₂ C(NO₂)₂--), 2.20 (S, 3H, --CH₃).

I.R. (fluorolube mull): ν_(max) =1777 cm⁻¹.

EXAMPLE 9 2,2-dinitropropyl-3-fluoro-3,3-dinitroethylcarbonate ##STR32##

To a solution of dinitropropyl chloroformate (5.74 g, 0.027 mol) andfluorodinitroethanol (3.08 g, 0.02 mol) in 25 ml of methylene chlorideat 4° was added with stirring a solution of pyridine (1.58 ml) inmethylene chloride (9 ml). The rate of addition was controlled so thatthe temperature did not rise above 8°. After the addition was completethe reaction mixture was stirred for 3 hours at ice bath temperature andan additional 3 hours at ambient temperature. The reaction mixture wasthen transferred to a separatory funnel with 50 ml of methylene chlorideand washed consecutively with 100 ml of dilute hydrochloric acid andfour 100 ml portions of water. The organic layer was dried (magnesiumsulfate) filtered and the solvents removed in vacuo. The residue wascrystallized from chloroform to give 6.0 g of product, 91% based onfluorodinitroethanol, m.p. 66°.

Calc for C₆ H₇ FN₄ O₁₁ ; C, 21.83; H, 2.14; F, 5.75; N 16.97. Found C,21.98; H, 2.15; F, 6.00; N, 16.77.

H-NMR (CDCl₃): δ=5.25 (d, 2H, CH₂ --CF), 5.00 (S, 2H, CH₂ C(NO₂)₂), 2.19(S, 3H, --CH₃).

I.R. (fluorolube mull); ν_(max) =1780 cm⁻¹.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A compound of the formula ##STR33## wherein Ris selected from the group consisting of --CH₂ C(NO₂)₃, --CH₂ CF(NO₂)₂,--CH₂ CF₂ (NO₂), --CH₂ CCl(NO₂)₂, --CH₂ CF₃, --CH₂ CCl₃, --CH₂ C(NO₂)₂CH₃, and --CH₂ CF₂ CF₂ H, and wherein R" is a lower alkyl group of from1 to 6 carbon atoms.
 2. The compound of claim 1 wherein R is --CH₂C(NO₂)₃.
 3. The compound of claim 2 which is S-ethyl 2,2,2-trinitroethylthiolcarbonate.
 4. The compound of claim 1 wherein R is --CH₂ CF(NO₂)₂.5. The compound of claim 4 which is S-ethyl 2-fluoro-2,2-dinitroethylthiolcarbonate.
 6. The compound of claim 1 wherein R is --CH₂ CF₂ (NO₂).7. The compound of claim 6 which is S-ethyl 2,2-difluoro-2-nitroethylthiolcarbonate.
 8. The compound of claim 1 wherein R is --CH₂ CCl(NO₂)₂.9. The compound of claim 8 which is S-ethyl 2-chloro-2,2-dinitroethylthiolcarbonate.
 10. The compound of claim 1 wherein R is --CH₂ C(NO₂)₂CH₃.
 11. The compound of claim 10 which is S-ethyl 2,2-dinitropropylthiolcarbonate.
 12. A compound of the formula ##STR34## wherein R" is alower alkyl group of from 1 to 6 carbon atoms.
 13. The compound of claim12 which is ##STR35##